I have no such regrets. You have to sell them to have regrets about it. With one exception, I haven't. And, no regrets about that one.

That definitely hurt!

Traded a Colt single action Army 2nd generation I bought new when I got out of the Army in 1971 for an Ithaca Mag 10 for goose hunting. Don't miss the Mag 10 but do miss the Colt. Paid $165 for the Colt

106312 , O Frame 28 Gauge DH Grade with Original 25" Barrels according to TPS it is the only 25" D Grade, 28 Gauge with 25" Barrels ! Like a Dummy ,I used it as a partial trade on a Parker 410 which I love but ...... ! Live and learn , when I made the deal I thought well it is an O Frame and I already have a OO Frame so that's what I did but I have regretted it since , I shot that gun better than any 28 Gauge I have owned !

There has been a few Guns I have regretted selling. Probably the one I
Miss the Most was the first centerfire rifle I bought with my own money. It
Was A Remington model 722 in 222 Magnum.
I have never found a rifle that I instinctively shot so well.

The gun I regret selling the most was a 0 frame 16ga GH Damascus from 1900 that was in almost new condition.
I made the mistake of taking it out on the opening day of dove season at farm that hosted a big event for the opener attended by by a bunch of hard core double gun collectors.
One of them hounded me for weeks, he finally made an offer I couldn’t refuse but should have.

My late father-in-law always shot a 12ga Remington Model 11, but he liked my doubles and decided he'd like to have one, "a 12ga, and not too expensive". I found him a really nice Fox Model B made in 1960 at a gun show and he loved it. One of his comments: "I like that it's got some weight to it", not something you hear much in double gun circles :)! Sadly his health had put him beyond his hunting years but I got to see him bust a few clays with it at the family spring-trap get togethers. After he passed my mother-in-law gave me the gun, but she's on a fixed income and I felt she could use the money more than I needed the gun so I sold it. I'm not much of a 12ga guy but it's the one gun I wish I still had.

Ditto. Maybe I should sell some but then the potential for sellers remorse is high. Let the kids sort it out at the end I guess.

I had forgotten I sold a circa 1906 Marlin 1893 32-40 with a half round half octagon barrel on GB a few years back . Guy in the UK bought it . That was the only 32-40 I've ever owned sometimes I think I'd like that one back .

Winchester Golden Grouse 20 gauge as new in its case and a Walther PP super.